Producing diolefins.



UNITED STATES PATENT OFFICE.

FRANZ WEIBEL, OF MANNHEIM, GERMANY, ASSIGNOR TO BAIDISC HE ANILIN & SODAFABRIK, OI! LUDWIGSHAFEN-ON-THE-RHINE, GERMANY, A CORPORATION.

PRODUCING DIOLEFIN S.

No Drawing.

Specification of Letters Patent.

Application filed January 30, 1912. Serial'No. 674,417.

Patented May 14, 1912 Toall whom it may concern Be it known that I,-FRANZ Wnnnn, subject of the King of Bavaria, residing at Mannheim,Germany, have invented new and useful Improvements in ProducinDiolefins,

of which the following is a speci cation.

In the J om'nal fiir Pmktz'sche Ohe'mc'e, (2), Vol. 55, page 5,Ipatieil' has described the production of a particular diolefin, viz. ofisoprene, by heating dibrom-isopentane with alcoholic potash. I havefound, however, that I can obtain much better yields of diolefins byheating a dihalogen paraffin with a solid compound which is capable ofsplit-ting oil halogen hydrid. The said solidcompound may effect thesplittin off of the halogen hydrid catalytically or y combining with thehalogen hydrid. As instances of compounds which can be employed for thussplitting ofl halogen hydrid, I mention barium chlorid, nickel chlorid,lead chlprid, alumina and caustic lime. The reaction is preferablycarried out by passing -a dihalogen paraflin in the state of vaporthrough a tube or the like containing the heated solid reagent, and itis also advantageous to carry out the reaction under reduced pressure.

The tube containing the barium chlorid or the like may, for. instance,be from about 1 to 3 yards in length.

The process ofthis invention is of particular advantage for theproduction of diolefins which can be employed in the roduction ofartificialcaoutchouc and simi ar bodies, for instance, diolefins .Whichcontain four, five, or six carbon atoms.

The following examples will serve to illus trate further the nature ofmy invention, which, however, is not confined to these examples. Theparts'are by weight;

Example 1: Vaporize trimethyl-ethylene bromid at a pressure of from 15to 20 millimeters and pass the vapor, slowly, over barium chlorid heatedto from 340 to 360 G.

Then pass the resulting vapors through a wash-bottle containing dilutelye in order to absorb the hydrogen bromid, and cool with a mixture ofcarbon dioxid and toluol at minus 80 O. In this way isoprene is obtainedof great purity and in very good yield. In a similar manner, isoprenecan be obtained from trimethyl-ethylene chl-orid (CH ,CCl-GHCl-GH orfrom 2.4-dibrom-Q-methyl-butane (CH CBrGH,--CH Br, or from3.4-dibrOm-Q-methyI-butane (on pon-onnr-omnr,

By passing their vapors over barium chlorid at, say from 20 to 50millimeters pressure, and at a temperature of from 300 to 500 0. Also bystarting from 2.3-dibrombutane, the corresponding butadien can beobtained ina similar manner.

Example 2: Pass vaporized trimethylethylene bromid at a pressure of 25Inillimeters, over'causti'c lime heated to from 430 to 450 C. In thisway pure isoprene is obtained in good yield.

Example 3: Pass vaporized 2.4-dibrom-2- methyl-butane 1. The process ofproducing diolefins by heating a dihalogen paraflin with a solidcompound which is capable of splitting oil halogen hydrid.

2. The process of producing diolefins by heating a dihalogen parafiinunder reduced pressure with a solid compound which is capable ofsplitting ofi' halogen hydrid.

3. The process of producin isoprene b heating trimethyl eth O y bariumchlorid.

4. The process of producing isoprene by lene-bromid with 4 from 340? to360 heating trimethyl ethylene bromid with In' testimony whereof I havehereunto "set barium chlorid under reduced pressure. my hand in thepresence'of two subscribing 5. The process of producing isoprene bywitnesses. passing vaporized trimethylethylene bro- FRANZ WEBEL. 5 midat a pressure of from 15 to 20 millime- Witnesses: A;

ters over barium chlorid at a temperature of O. TITTMANN,

- J. ALEC. LLOYD.

